interesting fact about katrina and lili

[Derek Ortt]

I was thinking this evening about Katrina and Lili and one interesting facet that has been overlooked about the two is they weakened at about the same rate (45kt for lili and 40kt for Katrina)

once we understand Lili, maybe Katrina's weakening will be explained. At least as a scientist I hope so so that the next time, we are not surprised (big difference was that Kat started out much more intense than Lili)

[ROCK]

If I remember right, didn't Lili fizzle out due to some dry air intake and increasing shear? She was pretty ominious during her days in GOM.

[Derek Ortt]

I think there was some increasing shear of Lili... plus, it moved into the northern GOM

Katrina and Lili weakened by about the same wind speeds (45KT for Lili and 40KT for Katrina... and based upon the data, it may have really weakened 45-50KT); thus, understanding what happened to Lili may explain what happened to Katrina

[Scorpion]

Only thing is Lili completely collapsed, Katrina still had a decent eye structure at landfall.

[ROCK]

Only thing is Lili completely collapsed, Katrina still had a decent eye structure at landfall.

Guess that depends on what you call decent. I think she was open to the sw when she made her first landfall. Still a good point. Lili imploded while Kat seemed to hold together more.

[Pearl River]

I found this abstract rather interesting:


ABSTRACT

The purpose of this paper is to compare the rapid intensification and rapid decay of Hurricane Lili with historical records to determine whether similar events have occurred in the past. Data for this study were compiled from the historical hurricane database that consists of all Atlantic basin tropical storms and hurricanes recorded from 1851 to 2001. Maximum 1-min sustained winds at 10 m were used. This study concludes that the rapid intensification/rapid decay processes that occurred as Hurricane Lili moved north across the Gulf of Mexico have been recorded only 11 other times since 1851. The intensification rate of 35 kt (1 kt = 0.5144 m s−1) in 24 h for Hurricane Lili ranked in the 11th percentile when compared with the 769 hurricanes in the historical database. In fact, 35.8% of all hurricanes that achieved an intensity of at least 100 kt intensified at a rate similar to Lili. The decay rate of 40 kt within 24 h after completion of rapid intensification ranks in the 1st percentile. This study also shows that all hurricanes in the Gulf of Mexico that rapidly intensified after 15 September proceeded to decay shortly thereafter by an average of 28 kt within 24 h of completion of rapid intensification. On the other hand, three of five (60%) hurricanes that rapidly intensified over the Gulf of Mexico prior to 15 September continued to intensify, by an average of 9 kt.



This is from The Rapid Intensification and Subsequent Rapid Weakening of Hurricane Lili as Compared with Historical Hurricanes
[/b]

[Audrey2Katrina]

I don't see the comparison. Katrina, according to NHC report went from 140 KT at 0000 UTC to 110 KT after initial landfall 12 hours later, (using a 12 hour window) which is exactly what was the yardstick by which Lili's decay was measured ( a 12 hour drop from mid range Cat 4 down to Cat 1 at landfall) Lili went from 125 KT to 80 KT, and that would indeed be a drop of 45 KT in a short 12 hour timespan--a much more rapid drop of a wider range in less time. What I seem to see with Katrina was a 30 KT drop in the same time period. Now IF you go all the way back to peak intensity instead of time lapse, it would be a 40 KT drop from the max speeds of 150 to the 110 over an 18 hour period of time, from 1800 UTC to 0600 the next day. I understand what you're trying to say; but I don't quite see the comparison as being all that strong. Also, as stated above, one was a late August storm, with warmer GOM temps than an early October storm; one was a Cape Verde storm (at least I think Lili was, perhaps you can clarify that), the other one which formed near the Bahamas, (don't know that the distance covered or water's traversed would make all that much difference, but just another variable), one was a much stronger Cat 5, the other a mid-range Cat 4 that all but collapsed by the time it hit landfall. I agree that what happened bears further and greater scrutiny; I just don't know that Lili would be the means whereby this sort of result can be attained.

Also, from the IR satellite imagery I've seen, Katrina most certainly kept a well defined circulation much better and far longer than did Lili.

A2K

[KWT]

I've got radar, sat and IR mages, hundreds of them from about 12hrs before landfall by the way so I'll look at.

(Right looked at it, it did get a little open on its south-western side just before landfall and the eye did fill somewhat but did keep its circulation really well, whats intresting is how the western side compeltely dies away bar the eyewall)

[ROCK]

I've got radar, sat and IR mages, hundreds of them from about 12hrs before landfall by the way so I'll look at.

(Right looked at it, it did get a little open on its south-western side just before landfall and the eye did fill somewhat but did keep its circulation really well, whats intresting is how the western side compeltely dies away bar the eyewall)

dry air......

[ROCK]

I don't see the comparison. Katrina, according to NHC report went from 140 KT at 0000 UTC to 110 KT after initial landfall 12 hours later, (using a 12 hour window) which is exactly what was the yardstick by which Lili's decay was measured ( a 12 hour drop from mid range Cat 4 down to Cat 1 at landfall) Lili went from 125 KT to 80 KT, and that would indeed be a drop of 45 KT in a short 12 hour timespan--a much more rapid drop of a wider range in less time. What I seem to see with Katrina was a 30 KT drop in the same time period. Now IF you go all the way back to peak intensity instead of time lapse, it would be a 40 KT drop from the max speeds of 150 to the 110 over an 18 hour period of time, from 1800 UTC to 0600 the next day. I understand what you're trying to say; but I don't quite see the comparison as being all that strong. Also, as stated above, one was a late August storm, with warmer GOM temps than an early October storm; one was a Cape Verde storm (at least I think Lili was, perhaps you can clarify that), the other one which formed near the Bahamas, (don't know that the distance covered or water's traversed would make all that much difference, but just another variable), one was a much stronger Cat 5, the other a mid-range Cat 4 that all but collapsed by the time it hit landfall. I agree that what happened bears further and greater scrutiny; I just don't know that Lili would be the means whereby this sort of result can be attained.

Also, from the IR satellite imagery I've seen, Katrina most certainly kept a well defined circulation much better and far longer than did Lili.

A2K

Yes, we all know there is no comparison to the almighty Katrina.

[KWT]

Well Katrina did become very loop-sided indeed, reminded me more of what tropical storms sometimes look like, only weak convection on the western side, here's one of the images, later on the eyewall opens up on the NW side as well as thwe western side further dies away as it makes landfall:

[ROCK]

Well Katrina did become very loop-sided indeed, reminded me more of what tropical storms sometimes look like, only weak convection on the western side, here's one of the images, later on the eyewall opens up on the NW side as well as thwe western side further dies away as it makes landfall:

Yes, indeed. The western side can be seen deteriorating due to dry air and some land interaction possibly. I don't remember the set-up but I think there was a trough squeezing her abit from the NW. Sort of like the tightening of the noose. Now her east side looks rather healthy. She consolidated much of her mid cat3 winds to that side along with her cat 5 surge.

[MiamiensisWx]

Another interesting fact is that Katrina was becoming somewhat elongated before landfall due to the encroaching shear from the front. The same thing occurred to Wilma, except the Wilma was intensifying before Florida landfall.

Another interesting thing is that land interaction may have actually helped Katrina maintain it's core and shape. If that land interaction were not there, Katrina might have weakened even more rapidly. Also, does anyone notice that Katrina looked like it was trying to become better organized at and just after landfall occurred and the center moved inland? After Katrina looked inland, deep convection was trying (or seeming) to fire around the eye, even on the western side.

[KWT]

Yes your right CapeVerdeWave, the eastern side weakened a tad but it becoame slightly more balanced though it was the case that the main convection was still on its eastern side, some deep convection did indeed fire up on its western eyewall.

[MiamiensisWx]

Yes your right CapeVerdeWave, the eastern side weakened a tad but it becoame slightly more balanced though it was the case that the main convection was still on its eastern side, some deep convection did indeed fire up on its western eyewall.

I agree... I think land interaction helped Katrina. These two floaters should show what I mean.

Here is what Katrina looked like just before it was making landfall. Notice how Katrina has become elongated in shape and convection has eroded, especially on the western side. Convection on the eastern side has weakened, too.



Contrast that loop with this one, which shows Katrina after it made landfall. Katrina seems to have become better organized. Notice how the shape has improved and how thew weakening of convection, including on the western side, has halted and balanced out. The eye/core shape has improved, and healthy convection is now starting to refire, even on the western side of the eye. Could land interaction have helped?



I really think land interaction helped Katrina to balance out instead of weakening further.

[Pearl River]

ROCK wrote

Audrey2Katrina wrote:
I don't see the comparison. Katrina, according to NHC report went from 140 KT at 0000 UTC to 110 KT after initial landfall 12 hours later, (using a 12 hour window) which is exactly what was the yardstick by which Lili's decay was measured ( a 12 hour drop from mid range Cat 4 down to Cat 1 at landfall) Lili went from 125 KT to 80 KT, and that would indeed be a drop of 45 KT in a short 12 hour timespan--a much more rapid drop of a wider range in less time. What I seem to see with Katrina was a 30 KT drop in the same time period. Now IF you go all the way back to peak intensity instead of time lapse, it would be a 40 KT drop from the max speeds of 150 to the 110 over an 18 hour period of time, from 1800 UTC to 0600 the next day. I understand what you're trying to say; but I don't quite see the comparison as being all that strong. Also, as stated above, one was a late August storm, with warmer GOM temps than an early October storm; one was a Cape Verde storm (at least I think Lili was, perhaps you can clarify that), the other one which formed near the Bahamas, (don't know that the distance covered or water's traversed would make all that much difference, but just another variable), one was a much stronger Cat 5, the other a mid-range Cat 4 that all but collapsed by the time it hit landfall. I agree that what happened bears further and greater scrutiny; I just don't know that Lili would be the means whereby this sort of result can be attained.

Also, from the IR satellite imagery I've seen, Katrina most certainly kept a well defined circulation much better and far longer than did Lili.

A2K


Yes, we all know there is no comparison to the almighty Katrina.

Here we go again. A person cannot make a comment without a smart@$$ comeback from someone.

[wxmann_91]

I really think land interaction helped Katrina to balance out instead of weakening further.

Could have some part, but more likely it was the completion of the ERC (Katrina was contracting as she was making MS landfall, as was demonstrated by KMOB radar), and interaction with a baroclinic trough that aided its poleward outflow. JMO.

[Audrey2Katrina]

Yes, we all know there is no comparison to the almighty Katrina.

Typical straw man response--but considering the source the only thing I know about all this is that you just never give up do ya!

A2K

[Audrey2Katrina]

I really think land interaction helped Katrina to balance out instead of weakening further.

Could have some part, but more likely it was the completion of the ERC (Katrina was contracting as she was making MS landfall, as was demonstrated by KMOB radar), and interaction with a baroclinic trough that aided its poleward outflow. JMO.

Good observation, and a better articulation of what I was thinking.

A2K

[thunderchief]

canes rapidly weakening as they landfall is the norm, rather than the exception, along the gulf coast, and indeed most places.